After workouts, the range of motion can be further increased as the increased muscle temperature increases the elastic properties of muscle and its stretch properties. (exercisegoals.com)
The hot water elevates body and muscle temperature enough to make them more receptive to stretching. (acefitness.org)
An enormous amount of heat is produced by skeletal muscle during running, and the body works hard to get rid of it; muscle temperatures of around 100 degrees Fahrenheit mean that vasodilation and evaporative cooling are a must to keep core temps down. (sbnation.com)